Coaxial connector



Jan. 30, 1968 R. c. LAUDIG ET AL I 3,366,920

COAXIAL CONNECTOR Filed Nov. 22, 1965 4 Sheets-Sheet 1 INVENTOR.

\ RONALD CLMR LAUDlG- FRANK BENJAMIN STARK Jan. 30, 1968 R. c. LAUDIG ET AL COAXIAL CONNECTOR 4 Sheets-Sheet Filed Nov. 22, 1965 INVENTOR. RONALD CLAIR LAumo- FRANK 35EN-IAMIN EJTARK Jan. 30, 1968 R. c. LAUDIG ET AL COAXIAL CONNECTOR 4 Sheets-Sheet 3 Filed Nov. 22, 1965 INVENTOR RONALD CLAIR LAUDQ- FRANK'BeuAAMm STARK BY Md, W

Jan. 30, 1968 R. c. LAUDIG ET AL 3,366,920

COAXIAL CONNECTOR Filed Nov. 22, 1965 4 ShesShee t 4 i INVENTOR. I

RONALD CLAm LAulMG- FRANK BENJAMIN STARK BY W W P 3,366,920 COAXIAL CONNECTOR Ronaid Clair Landig, Camp Hid, and Frank Benjamin Stark, Wormleysburg, Pa, assignors to AMP Incorporated, Harrisburg, Pa.

Filed Nov. 22, 1965, Ser. No. 509,114 11 Claims. (Cl. 339-477) This invention relates to the art of coaxial connectors and more particularly to a new and novel plug and receptacle for joining together two lengths of coaxial cable or shielded wire.

The particular construction of coaxial cable or shielded wire gives rise to several terminating problems which are not present in the termination of conventional insulated wire having a single conductor. A common type of coaxial cable consists of an inner conductor, which may be a solid or stranded wire, an outer conductor or metal braid, usually either plated or unplated copper, a dielectric used to correctly space and insulate the inner conductor from the metal braid, the metal braid being woven over the dielectric, and an outer protective covering, normally a tough material to protect and insulate the cable. In connecting two such cables together some of the problems which arise concern the establishment of electrical continuity between both the inner conductors of the two cables and the outer conductors or metal braids while maintaining these two electrical paths in sulated from each other; another problem being the compensation for impedance mismatches in the connector; another being the adaptability of the plug portion of the connector to mounting in panels of varying size; still another being in the manner of electrically connecting the two electrical paths to a printed circuit board.

One type of connector presently available for coaxial cable or shielded wire is described in application Ser. No. 336,969, filed Jan. 10, 1964, and having a common assignee with the instant invention. The connector of the instant application represents an improvement over the connector described in the above-identified application.

An object of the present invention is to provide a coaxial connector which compensates for impedance mismatches in the connector.

Another object of the present invention is to provide a plug assembly which can readily adapt to mounting in panels of varying thicknesses.

A further object is to provide means for grounding the receptacle portion of the connector to a printed circuit board or the like.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there are shown and described illustrative embodiments of the invention; it is to be understood, however, that these embodiments are not intended to be exhaustive nor limiting of the invention but are given for purpose of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings, in which like reference numerals refer to like parts:

FIGURE 1 is an exploded perspective view of the plug portion of the connector of the present invention;

FIGURE 2 is a perspective view of the plug of FIG- URE 1 showing the parts in their assembled condition;

FIGURE 3 is an exploded perspective view of the receptacle portion of the connector;

FIGURE 4- is a perspective view of the receptacle of States Patent C) FIGURE 3 showing the parts in their assembled condition;

FIGURE 5 is a longitudinal cross-sectional view of the plug and receptacle assemblies;

FIGURE 6 is a longitudinal cross-sectional view showing the plug and receptacle assemblies in their mated position;

FIGURE 7 is a perspective view showing a series of receptacle assemblies mounted on a printed circuit board or the like; and

FIGURE 8 is an alternative embodiment of a grounding clip used in conjunction with the receptacle as shown in FIGURE 7.

Turning first to FIGURES 1 and 2 there is shown a plug assembly 1'!) adapted to be mounted in a panel member 12. The plug assembly comprises a hollow outer shell 14 made of a suitable metal and receiving therein a dielectric spacer 16. The dielectric 16 serves to properly space the electrical paths of the inner conductor and outer braid of the coaxial cable. A plurality of spring fingers 18 are integrally formed on one end of shell 14, the end of the fingers 18 lying in the recess portion 26 of spacer 16. The spring fingers 18 mate with the receptacle portion of the connector as will become apparent as this description proceeds.

A center contact 22, made of copper or other suitable material, is disposed within the central aperture 24 of spacer 16. The contact 22 receives therein the center conductor 26 of a coaxial cable or shielded wire. A barb 28 is disposed around the periphery of contact 22, the barb serving to maintain the contact in its proper position within spacer 16. As seen in FIGURE 5 the barb will bite into the inner surface of spacer 16 and thus prevent the contact from being dislodged upon insertion of the conductor 26 therein. As seen in FIGURES 5 and 6 the contact 22 is crimped onto center conductor 26 to insure proper electrical connection therewith. Since the crimping operation is performed after the contact is assembled within spacer 16 and outer shell 14 provision must be made to allow the jaws of a crimping tool to communicate with the contact 22. For this purpose a pair of portholes 30 and 32 are formed in the spacer 16 and outer shell 14 respectively.

The shell 14 has a reduced diameter end portion 34 around which is placed the metal braid or outer conductor 36 of the coaxial cable. To firmly secure the metal braid 36 to the end portion of the shell, there is provided a ferrule 38. The ferrule 38 is crimped to both the end portion 34 of the shell 14 and also to the outer insulation 40 of the coaxial cable to thereby eifect proper electrical and mechanical connection between the cable and the outer shell.

For mounting the plug assembly 10 within panel 12 there is provided a mounting bushing 42 which is made of a suitable insulating material. It is to be noted that although the mounting bushing 42 is normally an electrical insulator, it may be formed out of metal in those applications wherein it is desired to ground the outer braid of the coaxial cable to the panel 12. The bushing 42 fits over the central portion of shell 14 and passes through an aperture 44 in the panel 12. A series of threadlike rings 46 are formed around the periphery of bushing 42 for cooperation with a locking collar 48. The collar 48 is formed of a somewhat flexible plastic material, such as nylon, and has an inner tooth 56 for engaging one of the rings 46 on bushing 42. The diameter of aperture 44 is made slightly larger than the diameter of bushing 42 so that the plug is permitted a limited amount of floating action when assembled within the panel 12, thus compensating for any possible misalignment between the plug assembly and its corresponding receptacle. By virtue of the plurality of rings 46 on the bushing, the plug assembly can be mounted in panels of varying thickness.

The spacing between the center conductor and outer braid of the coaxial cable determines the impedance value of the cable and this impedance value should be maintained constant through the connector in order to obtain a clear output signal through the cable. As can be seen in FIGURE 5 the outer shell 14 is so dimensioned that the ratio between its inner diameter and the outer diameter of the center conductor 26, and the center contact 22, is maintained constant. However, due to the porthole 30 in spacer 16 there is an area between the center contact and outer shell which is devoid of dielectric material. This void represents a high impedance area and must be corrected for. The impedance through the connector may be calculated by the formula where Z is the impedance, [2 is the inner diameter of the outer shell 14, a is the outer diameter of the center contact, and K is the dielectric constant of the material lying between the center contact and outer shell. Since air has a very low dielectric constant, it can be seen that this void would present a high impedance area. To compensate for this, a pair of ribs 52 are formed on the inner surface of bushing 42 and these ribs will fit into the void area caused by the porthole 30. The bushing 42 is split longitudinally to allow it to be snapped into position around the outer shell. It can be seen that the ribs 52 serve the twofold purpose of retaining the bushing relative to the outer shell and also for compensating for the impedance mismatch in the connector. The impedance through the porthole area can thus be controlled at will by the proper selection of the material from which the bushing is made. The material selected will also determine the degree to which the ribs fill these voids.

The receptacle assembly 54 is best shown with reference to FIGURES 3 and 4. An insulated block or housing 56 is provided having a central aperture 58 therethrough and a .pair of depending legs 60 for positioning the housing on a printed circuit board 62. A metallic outer shell 64 is positioned within aperture 58 and has a circumferential flange 66 thereon for longitudinally positioning said shell relative to said housing, as seen in FIGURE 5. A retaining member 68 is positioned around outer shell 64 and has a plurality of lances 70 disposed around the periphery thereof, the said lances cooperating with an inner wall 72 of the housing 56 to thus maintain the outer shell within the housing. The resiliency of the lances permits a limited degree of floating action of the outer shell and thus of the receptacle assembly to allow for any misalignment between the plug assembly and receptacle assembly 54. The retaining member 68 has a similar function to the mounting bushing 42 previously described in connection with the plug assembly. Member 68 may be made of nylon or other insulating material and is provided with a pair of ribs 74 which pass through portholes 76 in the outer shell 64 to compensate for impedance mismatch in the receptacle assembly in the same manner as previously described in connectionwith the ribs 52 on bushing 42. It is noted that in some instances it may be desirable to ground the outer braid of the cable leading into the receptacle assembly to a metallic panel or the like. In such instances the retaining member 68 would be made of a metallic material, such as copper, and the housing 56 would be replaced by a metallic wall.

Turning again to FIGURES 3 and 4 there is shown a dielectric spacer 78 which is received within outer shell 64, spacer 78 having a pair of portholes 80 therein which portholes register with the portholes 76 in the outer shell to define the void area which will be filled by the ribs 74 on member 68. A center contact 82, made of brass or like material, is inserted into the central aperture 84 of spacer 78, the said contact having a barb 86 disposed around log 13 a the periphery thereof which barb will engage the inner surface of spacer 78, as shown in FIGURE 5, to maintain the contact in position within the spacer when the center conductor 88 of a coaxial cable is inserted within the end of contact 82. The center contact 82 is crimped onto conductor 88 through the portholes 76 and 88 in a similar manner as the center contact 22 previously described. The braid 90 of the coaxial cable is positioned over an end portion 92 of the outer shell 64 and is secured thereto by means of a ferrule 94 which is crimped around both the braid portion of the cable and the outer insulation as indicated in FIGURES 5 and 6.

In FIGURE 6 the plug assembly and receptacle assembly are shown in their mated position and as can be seen the spring fingers 18 of the plug assembly engage the inner surface of shell 64 and are flattened thereby to provide electrical continuity between the metal braid of the two cables. Further, the center contact 82 is inserted within center contact 22 to thereby establish electrical continuity between the center conductors 26 and 88 of the two cables.

In many instances it is desirable to mount the receptacle assemblyv onto a printed circuit board in such a manner that a right angle connection is made, that is both the center conductor and outer braid are led at right angles through the board. In FIGURE 7 there is shown three receptacle assemblies 96, 9'8 and mounted on a printed circuit board 102. The receptacle assembly 96 is shown having a cable 104 extending therefrom and parallel to the board 102. In contrast assemblies 98 and 100 are mounted for right angle connection to the board, the assembly 98 being shown in an exploded manner for the sake of clarity. In order to ground the metallic braid in assemblies 98 and 100' there is provided a clip 106 which surrounds the end 92 of the outer shell 64, the said clip having a depending leg 108 which passes through an opening 110 in the printed circuit board for electrical connection with a conductor on the lower surface of the said board. The configuration of clip 106 provides a considerable degree of resiliency so as not to interfere with the floating action permitted by the retaining member 68 previously described.

In FIGURE 8 there is shown an alternative embodiment of a grounding clip 112, the clip 112 being similar to clip 106 with the exception that the increased curvature of the clip allows a greater degree offloating action than does the clip106. In all other respects the clip 112 functions in the same way as clip 106.

It can thus be seen that a plug assembly and receptacle assembly have been provided which are readily mountable on either a panel or a printed circuit board and will provide for a constant impedance value through the connector to thereby eliminate any distortion in the signal carried by the cables. Further, the assemblies are capable of a limited degree of floating action whereby any misalignment tolerances are compensated for. In addition the grounding clips 106 and 112 provide a simple and compact means for grounding the metal braid of a cable to a printed circuit board.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

We claim:

1. A plug assembly comprising an outer shell having a pair of crimping portholes therein, a dielectric spacer disposed within said outer shell and having a pair of crimping portholes which are in alignment with the portholes on said shell when said spacer is positioned within said shell, a contact disposed within said spacer for receiving the center conductor of a coaxial cable, said contact being crimped to said center conductor for mechanical and electrical connection therewith, said shell further having an end portion which receives the metal braid of said coaxial cable, means for connecting said metal braid to said end portion, and a mounting bushing disposed around said outer shell, said bushing having a pair of ribs of dielectric material on the internal surface thereof, said ribs extending into the porthole area of said spacer and said outer shell to compensate electrically for any impedance mismatch in said plug assembly.

2. A plug assembly as set forth in claim 1 further comprising a barb disposed on the periphery of said contact, said barb engaging the inner surface of said spacer for securing the contact in position Within said spacer.

3. A plug assembly as set forth in claim 1 further comprising a series of rings disposed around the periphery of said bushing, and a collar having means for engaging the rings on said bushing for positioning said plug assembly within a panel member.

4. A plug assembly as set forth in claim 3 wherein said bushing is disposed Within an aperture in said panel member, the diameter of said aperture being slightly greater than the outside diameter of said bushing, whereby said plug assembly is capable of a limited degree of floating action to compensate for any misalignment between said plug assembly and a mating connector.

5. A plug assembly as set forth in claim 1 wherein said bushing is formed of a dielectric material whereby the dielectric constant of the ribs of said bushing determines the impedance of said plug assembly through said porthole area.

6. A receptacle assembly comprising an outer shell having a pair of crimping portholes therein, a dielectric spacer disposed within said outer shell and having a pair of crimping portholes which are in alignment with the portholes in said outer shell when said spacer is disposed within said outer shell, a contact disposed Within said spacer for receiving the center conductor of a coaxial cable, said contact being crimped to said center conductor, means for securing the metal braid of said coaxial cable to one end of said outer shell, a housing having a central aperture therethrough for receiving said outer shell, and a retaining member disposed around said outer shell for positioning said outer shell within said housing, said retaining member having resilient means for engaging an inner surface of said housing to permit a limited degree of floating action of said outer shell Within said housing, said retaining member further having a pair of ribs of dielectric material on the inner surface thereof, said ribs extending into the porthole area of said spacer and said outer shell to thus compensate for any impedance mismatch through said receptacle assembly.

7. A receptacle assembly comprising an outer shell having a pair of crimping porthole-s therein, a dielectric spacer disposed within said outer shell and having a pair of crimping portholes in alignment with the portholes in said outer shell, a contact disposed within said spacer for receiving the center conductor of a coaxial cable, said contact being crimped to said center conductor, means for securing a metal braid of said cable to said outer shell, a housing having a central aperture therein for receiving said outer shell, and a retaining member disposed around said outer shell and having resilient means disposed on the periphery thereof for engaging said housing and thus permitting a limited degree of floating action of said outer shell relative to said housing, said retaining member further having a pair of ribs of dielectric material on the inner surface thereof, said ribs extending into the porthole area of said spacer and said outer shell to thus compensate for any impedance mismatch through said receptacle assembly.

8. A receptacle assembly comprising an outer shell having a pair of crimping portholes therein, a dielectric spacer disposed Within said outer shell and having a pair of crimping portholes, the portholes in said spacer being in alignment with the po-rtholes in said outer shell, a contact disposed within said spacer for receiving an electrical conductor, said contact being crimped to said electrical conductor through said portholes, a housing having an aperture therethrough for receiving said outer shell, said housing having means for positioning said housing on a printed circuit board, a retaining member disposed around said outer shell and having resilient means thereon for engaging an inner surface of said housing, said resilient means permitting said outer shell a limited degree of floating movement relative to said housing, said retaining member further having a pair of ribs of dielectric material on the inner surface thereof, said ribs extending into the porthole area of said spacer and said outer shell to thus compensate for any impedance mismatch through said receptacle assembly, and a metallic clip disposed around an end portion of said outer shell, said clip having a depending leg which extends through said printed circuit board to thus ground said outer shell to said printed circuit board.

9. A receptacle assembly as set forth in claim 8 Wherein said clip is formed of thin resilient material to permit floating action of said receptacle relative to said printed circuit board.

10. A receptacle assembly as set forth in claim 8 Wherein said contact has a barb disposed on the periphery thereof for engaging the inner surface of said spacer, said barb preventing said contact from being dislodged from said spacer.

11. An electrical connector comprising a plug assembly and a receptacle assembly; said plug assembly comprising an outer shell having a pair of crimping portholes therein, a dielectric spacer disposed within said shell and having a pair of crimping portholes which are in alignment with the portholes on said outer shell, a contact disposed within said spacer for receiving the center condoctor of a coaxial cable, said contact being crimped to said center conductor through said portholes, means for securing the metal braid of said cable to said outer shell, a bushing disposed around said outer shell and having a pair of ribs of dielectric material extending into the porthole area of said spacer and said outer shell to compensate for impedance mismatch in said plug assembly, a collar cooperating with said bushing for mounting said plug as sembly in a panel, said outer shell fur-ther comprising a plurality of resilient fingers on one end thereof; said receptacle assembly comprising an outer shell having a pair of crimping portholes therein, a dielectric spacer disposed within said outer shell and having a pair of crimping portholes in alignment with the portholes on said outer shell, a contact disposed within said spacer for receiving an electrical conductor, said contact being crimped to said electrical conductor through said portholes, a housing having an aperture the-rein for receiving said outer shell, a retaining member disposed around said outer shell and having resilient means for engaging the inner surface of said housing for permitting a limited degree of floating movement of said receptacle relative to said housing; said plug assembly being insertable within said receptacle assembly whereby the plug contact mates with the receptacle contact and the resilient fingers of said plug outer shell engage the inner surface of said receptacle outer shell to thereby establish electrical continuity of the electrical paths through said center conductors and said outer shells.

References Cited UNITED STATES PATENTS 2,758,065 '10/1960 Flanagan 339-17 3,103,548 9/1963 Concelman 339-177 X 3,235,834 2/1966 OKeefe et al. 339177 3,323,098 5/1967 OKeefe et al 339l77 MARVIN A. CHAMPION, Primary Examiner.

J. R. MOSES, Assistant Examiner. 

1. A PLUG ASSEMBLY COMPRISING AN OUTER SHELL HAVING A PAIR OF CRIMPING PORTHOLES THEREIN, A DIELECTRIC SPACER DISPOSED WITHIN SAID OUTER SHELL AND HAVING A PAIR OF CRIMPING PORTHOLES WHICH ARE IN ALIGHMENT WITH THE PORTHOLES ON SAID SHELL WHEN SAID SPACER IS POSITIONED WITHIN SAID SHELL, A CONTACT DISPOSED WITHIN SAID SPACER FOR RECEIVING THE CENTER CONDUCTOR OF A COAXIAL CABLE, SAID CONTACT BEING CRIMPED TO SAID CENTER CONDUCTOR FOR MECHANICAL AND ELECTRICAL CONNECTION THEREWITH, SAID SHELL FURTHER HAVING AN END PORTION WHICH RECEIVES THE METAL BRAID OF SAID COAXIAL CABLE, MEANS FOR CONNECTING SAID METAL BRAID TO SAID END PORTION, AND A MOUNTING BUSHING DISPOSED AROUND SAID OUTER SHELL, SAID BUSHING HAVING A PAIR OF RIBS OF DIELECTRIC MATERIAL ON THE INTERNAL SURFACE THEREOF, SAID RIBS EXTENDING INTO THE PORTHOLD AREAS OF SAID SPACER AND SAID OUTER SHELL TO COMPENSATE ELECTRICALLY FOR ANY IMPEDANCE MISMATCH IN SAID PLUG ASSEMBLY. 